Rheostat.



No. 687,569. Patented NOV. 26, |90l.

J. LUNDIE. nHEnsTAT. (Application led Aug, 15, 1901.) (No Model.) 2 Sheets-Sheet 2.

Flg- 5'- Witnesses: Invent r ww )fm2/ p unit, `and Fig. 7 is a diagram showing one UNITED STATES PATENT OEEICE.

lJOHN LUNDIE, OF NEW YORK, N. Y.

RH EOSTAT.

'sPEcIFIcA'TIoN 'forming .part of Lettere Patent No. 687,569, dated November 2e, 1901.

Application filed August l5, 1901. Serial No. 72,130. (No model.) Y

To MIZ whom it may concern:

Beitknown that I, JOHN LUNDIE, a citizen of the United States of America, and a resident of New York city, inthe county and State of New York, have invented certain new and useful Improvements in Rheostats, of which the following is a specification.

This invention relates to rheostats for use in regulating the amount of current flowing through an electric circuit in which it is interposed, designed more especially for use in connection with electric motors used in traction systems.

The principal objects of the invention may be said to consist in the simplified construction of the rheostat, enabling the ready assemblage of the parts; in providing resistance units, each of which has a minimum amount of support and which is otherwise self-supporting; providing an extensive surface, so that the ventilation permitted by spaces between the units and the convolutions thereof may have a maximum cooling effect; in avoiding the necessity of making any special electrical connection between the resistance units, these being preferably so constructed as that an electrical contact is established directly one unit is assembled with another; in assembling the units-ordinarily of spiral form-in succession in reverse order, so that the direction of current is such as to create a cumulative magnetic field in the same direction which on changing will produce an inductive effect, and in the generally durable, practical, and economical construction of the rheostat.

The invention consists of certain novel features to be hereinafter described in detail and then claimed.

In the accompanying drawings, Figure lis a sectional end elevation of a rheostat embodying the preferred form of the invention; and Fig. 2 is a side-elevation thereof, partly in section. Fig. 3 is a sectional end elevation showing a modification; and Fig. 4 is a side elevation thereof, parts being sectioned. Figs. v5 and 6 are respectively edge and plan views of the preferred form of resistance application of the rheostat.

Referring tothe drawings, Figs. l, 2, 5, and

6 in particular, the rheostatin question comprises co'nducting resistance units A, cast o'r formed with two coils or spirals a a', connected in the form of a double scroll at a2. The crosssection of any convolution of the spiral is ordinarily tapering, as shown. The inner ends of the spirals are formed with hubs l), which may or may not be thickened at both sides, so as to form bosses, said hubs being provided with central apertures b', Fig. 6. Intermediate centrally-apertured hubs b: are form ed in the connection a2 between the individual spirals of the resistance units. This construction is adopted when the means of support for the spirals is substantially as shown. Ordinarily hangers or brackets C, connected by three rods D and by tie-rods C', are einployed. The tierods O are entirely outside of the resistance, and the resistance units A are strung one after the other upon the three rods D, the two outside rods D passing through the apertures b of hubs h and the intermediate rod through the hubs b2. Between some of the hubs of the adjacent resistance units insulating-washers E are interposed, and ordinarily metallic washers E are interposed between other of the hubs; but if' the appropriate hubs be made thick enough these washers E may be dispensed with, or if the hubs are not thickened thicker metallic washers would be used for making the electrical connection. The supporting-rods D are each sheathed with an insulation-sleeve D', which insulates the resistance units therefrom. When the resistance units and spacing-washers are properly assembled, they are clamped up tightly between the hangers by means of nuts which are screwed onto the threaded ends of the rods D.

As shown in Figs. l, 2, and 7, the electrical connection is in series; but it may be either series or parallel, as required. The electrical connection is here shown at alternate opposite ends of the successive spiral resistance units, so that the current is made to traverse one spiral after the other. Ordinarily the spirals are assembled in succession in reverse order. The consequence then is that the direction of the current is such as to create a cumulative magnetic field in the same direction which on changing will produce an inductive eect. ln the double-spiral form the current iiows oppositely in the individual IOO cameo spirals or coils belonging to the set at one side toits direction in the set at the other side. It is obvious thatinstead of mounting the resistance units in reverse order, as shown, they may be mounted in the saine order, so that corresponding convolutions will lie directly opposite each other for non-inductive effects.

In a modified and simplified form of the iuvention (shown in Figs. 3 and 4) single spirals are shown, and these may be mounted in the same or reverse order. The single spirals A are strung with properly-interposed insulating and metallic washers E2 E3 (if the latter be used) upon the insulated rods D2 D3, which are supported in hangers C2. In all respects the general construction and principle of the resistance shown in Figs. 3 and 4 are the same as before, as will be understood, as if especially described in detail.

The insulating-washers and the thickened hubs or metallic Washers,whether they be used separately or conjointly, providing means for spacing the resistance units at suitable intervals apart, and the self-supporting nature of each spiral, with the exception of the mini-` mum amount of support provided, providing means for spacing the convolutions of such spiral at suitable intervals apart, it follows that corresponding air-spaces are formed for insulation and ventilation, while, due to the form of the resistance, an inductive effect is given on the starting, stopping, or changing of the electric current.

In Fig. 7 the practical use of the resistance is shown in an electric circuit embodying a line-'switch II, a motor I, and a controller J.

It will occur to those skilled in the art that various changes in the form of the invention shown may be madeas, for instance, in the form of support; but I do not intend to limit my invention to the construction as shown.

Where the word spiral is`used in the claims, it is not the intention to limit the invention to a spiral of continuous curvature; but any form of wire or strip winding from the inside to the outside in turns in the same general direction after the manner of a spiral is intended to be included.

Vhat I claim as new, and desire to secure by Letters Patent, is v l. In a rheostat, the combination of a plurality of spiral resistance units, electrically connected alternately at their adjacent inner ends and their adjacent outer ends, and constructed with Ventilating and insulating airspaces between the convolutions, and means for supporting and spacing the units apart, so as to provide additional Ventilating and insulating air-spaces, such units having a minimum amount of support and being otherwise self-supporting.

2. Ina rheostat, the combination of a plu rality of spiral resistance units, means for supporting and spacing the units apart, such spiral resistance units being assembled in succession and electrically connected in reverse order, so that the current is caused to flow in such direction as to cumulatively magnetize in the same direction and so produce a maximum inductive effect on change of cu rrent.

3. In a rheostat, the combination of a plurality of spiral resistance units, means for supporting and spacing the units apart, such spiral resistance units being assembled in succession and electrically connected in reverse order so that the current is caused to flow in such direction as to cumulatively magnetize in the same direction and so produce a maximum inductive effect on change of current, air-spaces for ventilation and insulation being formed between the convolutions of each spiral and between the juxtaposed spirals.

4. In a rheostat, a ventilated inductive re-l sistance, composed of spiral resistance units alternately connected in series at their adjacent inner ends and their adjacent outer ends.4

5. In a rheostat, the combination, with a supporting-rod, of a plurality of spiralconducting resistance units strung upon and in# sulated from the rod, such units being electrically connected alternately at their adja-y cent inner ends and their adjacent outer ends.

6. In a rheostat, the combination, with two supporting-rods, of a plurality of spiral con# ducting resistance units, apertured and insulated from said rods, such units being suitably insulated at appropriate ends.

7. A rheostat unit,- eonsisting of a conducting resistance-spiral provided with a thickened hub at one end.

8. A rheostat unit, consisting of two con# ducting resistance-spirals in scroll form.

9. A rheostat unit, consisting of two conducting resistancespirals in scroll form, provided with thickened hubs at the supporting ends.

l0. A rheostat unit,- consisting of two fiattened conducting resistance-spirals in scroll form.

ll. A rheostat unit, consisting of two con'- ducting resistance-spirals in scroll form, pro# vided with thickened apertured hubs at the points of support.

l2. A rheostat unit, consisting of two conducting resistancespirals in scroll form, pro-- vided with apertures in the inner ends of the' spirals.

13. A rheostat unit, consisting of two con ducting resistance-spirals in scroll form, provided with three apertures, two in the inner ends of the spirals, and one between the spirals.

14. In a rheostat, the combination, with two supporting-rods, of a plurality of conducting resistance units, each composed of two spirals united in scroll form, such units having apertures for the rods, and being insulated from the rods.

l5. Inarheostat, the combination, with two supportingsrods, of a plurality of conducting resistance units, each composed. of two spirals united in scroll form, such units having apertured and thickened hubs at the centers of the spirals for receiving the rods, from which they are insulated.

16. In a rheostat, the combination, with three supporting-rods, of a plurality of conducting resistance units, each composed of two spirals united in scroll form and each unit having apertured hubs at the centers of the spirals, for receiving the two outer rods, and between the spirals for receiving the intermediate rod said rods being insulated from the resistance units.

17. In a rheostat, the combination with a plurality of spiral resistance units alternately connected at their inner and their outer ends, of means for supporting and spacing said units apart.

Signed at New York, N. Y., this 13th day 3o of August, 1901.

JOHN LUNDIE.

Witnesses:

GEO. B. CORNELL, GEO. S. WEEELooK. 

